Abstract. The proposed study uses community-based participatory research (CBPR) to develop a webnovela, which we define as an internet-based serial drama (modeled after the time-limited soap operas popular in Latin America), and examines the feasibility and acceptability of the webnovela as an intervention to increase HIV testing among men who have sex with men (MSM) in Colombia. This study builds upon our previous research, which identified an urgent need to increase detection of HIV among Colombian MSM, who constitute the country?s most highly affected group. Based on the communication strategy of entertainment-education, transportation-imagery theory, and information avoidance theory, the goal of this project is to create an engaging entertainment vehicle with embedded information and social messages that alter viewers? knowledge, attitudes, behavior, and social norms relative to HIV testing. The specific aims are 1) to develop a webnovela (seven 13-minute episodes) to increase HIV testing among HIV-negative or HIV-status-unknown Colombian MSM, ages 18 to 30 years; and 2) to examine the feasibility and acceptability of the webnovela intervention in this group. The CBPR Team?consisting of individuals from the MSM community, representatives from gay community organizations, experts in communication for social and behavioral change, and the researchers?will be actively involved in all stages of development of the webnovela, including formative background research, message identification and clarification, creation of the broad story line, and review of scripts and production. Qualitative research, consisting of five focus groups (10 per group, N=50) and 15 key informant interviews, will provide additional community input to guide the development of the webnovela. Respondent-driven sampling will be used to recruit participants (N=150) for the test of feasibility of the webnovela intervention. We will examine feasibility and acceptability qualitatively and quantitatively. All participants will respond to a computerized baseline survey prior to viewing the webnovela and will answer questions concerning narrative engagement after viewing the final episode. In-depth interviews with 30 participants will provide detailed reactions to the content, plot, and characters of the webnovela. A 6-month follow-up computerized survey (with the remaining 120 participants) will assess enduring reactions to the webnovela, HIV testing in the previous six months, as well as topics covered in the baseline survey, which include knowledge of HIV transmission, perceived norms and attitudes toward HIV testing, and sexual risk behavior. Other data will capture participants? viewing times and patterns, as well as reactions to individual episodes. Research questions will examine feasibility and acceptability of the webnovela, including the extent to which participants watch the program, the webnovela?s ability to create narrative engagement, and the potential for diffusion. In addition, the study will explore in a preliminary manner the efficacy of the intervention to increase HIV testing, as well as possible mechanisms underlying any change in testing behavior.